Liquid meniscus lens with concave torus-segment meniscus wall

ABSTRACT

The present invention relates generally to a liquid meniscus lens with a meniscus wall. Some specific embodiments include a liquid meniscus lens with a meniscus wall essentially in the shape of a conical frustum with at least a portion of the conical frustum concave toward the optical axis. Embodiments may also include a lens of suitable size and shape for inclusion in a contact lens.

RELATED APPLICATIONS

This application claims priority to Provisional U.S. Patent ApplicationSer. No. 61/368,868, filed on Jul. 29, 2010.

FIELD OF USE

The present invention relates generally to a liquid meniscus lens, morespecifically, it includes a liquid meniscus lens, such as, an arcuateliquid meniscus lens, with a concave torus-segment meniscus wall.

BACKGROUND

Liquid meniscus lenses have been known in various industries. Asdiscussed more fully below with reference to FIGS. 1A and 1B, knownliquid meniscus lenses were engineered in cylindrical shapes with aperimeter surface formed by points at a fixed distance from an axiswhich is a straight line. Known liquid meniscus lenses have been limitedto designs with a first interior surface generally parallel to a secondinterior surface and each perpendicular to a cylindrical axis. Knownexamples of the use of liquid meniscus lenses include devices such aselectronic cameras and mobile phone devices.

Traditionally, an ophthalmic device, such as a contact lens and anintraocular lens included a biocompatible device with a corrective,cosmetic or therapeutic quality. A contact lens, for example, canprovide one or more of: vision correcting functionality; cosmeticenhancement; and therapeutic effects. Each function is provided by aphysical characteristic of the lens. A design incorporating a refractivequality into a lens can provide a vision corrective function. A pigmentincorporated into the lens can provide a cosmetic enhancement. An activeagent incorporated into a lens can provide a therapeutic functionality.

More recently, electronic components have been incorporated into acontact lens. Some components can include semiconductor devices.However, physical constraints including the size, shape and controlaspects of a liquid meniscus lens have precluded their use in anophthalmic lens. Generally the cylindrical shape, sometimes referred toas the “hockey puck” shape of liquid meniscus lenses, has not beenconducive to something that can work in a human eye.

In addition, a curved liquid meniscus lens includes physical challengesthat are not necessarily present in a traditional design of a liquidmeniscus lens with parallel sidewalls.

SUMMARY

Accordingly, the present invention provides a liquid meniscus lens. Somepreferred embodiments include an arcuate front curve lens and an arcuateback curve lens. The present invention provides for a meniscus wall withphysical features conducive for one or both of attraction and repulsionof a liquid contained within the lens and forming a meniscus withanother liquid.

According to the present invention, a first optic is proximate to asecond optic with a cavity formed therebetween. Preferred embodimentsinclude a first arcuate shaped optic proximate to a second arcuateshaped optic with a cavity formed therebetween. A saline solution and anoil are maintained within the cavity. Application of an electricalcharge to a meniscus wall generally located in a perimeter area of oneor both of the first optic and the second optic changes the physicalshape of a meniscus formed between the saline solution and oilmaintained within the cavity.

The present invention includes a meniscus wall formed into a shapeessentially including a segment of a torus. A cross section of thetorus-segment includes a concave shaped wall. The present inventionadditionally teaches unique operation of a liquid meniscus lensincluding effects imparted by a convex formation of the meniscus wall.

DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a prior art example of a cylindrical liquid meniscuslens in a first state.

FIG. 1B illustrates the prior art example of a cylindrical liquidmeniscus lens in a second state.

FIG. 2 illustrates a profile sliced cut away of an exemplary liquidmeniscus lens according to some embodiments of the present invention.

FIG. 3 illustrates a cross section of a portion of an exemplary arcuateliquid meniscus lens, according to some embodiments of the presentinvention.

FIG. 4 illustrates additional exemplary aspects of an arcuate liquidmeniscus lens.

FIG. 5 illustrates meniscus wall elements within an arcuate liquidmeniscus lens, according to some embodiments of the present invention.

FIG. 6A illustrates a concave meniscus wall within a liquid meniscuslens, showing a liquid meniscus boundary in an unpowered state.

FIG. 6B illustrates a concave meniscus wall within a liquid meniscuslens, showing a liquid meniscus boundary in a powered state.

FIG. 6C illustrates a concave meniscus wall within a liquid meniscuslens, showing a powered and an unpowered state of a liquid meniscusboundary in a single diagram for comparison.

FIG. 7 illustrates a concave torus-segment, which is the shape of aconcave meniscus wall when viewed separately from the rest of thearcuate liquid meniscus lens.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides for a liquid meniscus lens with at leastone of a front curve lens and a back curve lens defining a meniscuscavity of the liquid meniscus lens.

GLOSSARY

In this description and claims directed to the presented invention,various terms may be used for which the following definitions willapply:

Contact Angle: The angle at which the oil/saline solution interface,also referred to as the liquid meniscus boundary, meets the meniscuswall. In the case of a linear meniscus wall, the contact angle ismeasured as the angle between the meniscus wall and the line tangent tothe liquid meniscus boundary at the point where the liquid meniscusboundary meets the meniscus wall. In the case of a curved meniscus wall,the contact angle is measured as the angle between the lines tangent tothe meniscus wall and the liquid meniscus boundary at the point wherethey meet.

Liquid Meniscus Boundary: The arcuate surface interface between thesaline solution and the oil. Generally, the surface will form a lensthat is concave on one side and convex on the other.

Meniscus Cavity: The space in an arcuate liquid meniscus lens betweenthe front curve lens and the back curve lens in which oil and salinesolution are maintained.

Meniscus Wall: A specific area on the interior of the front curve lens,such that it is within the meniscus cavity, along which the liquidmeniscus boundary moves.

Optical Zone: as used herein refers to an area of an ophthalmic lensthrough which a wearer of the ophthalmic lens sees.

Sharp: A geometric feature of an internal surface of either a frontcurve or back curve lens piece sufficient to contain the location of acontact line of two predefined fluids on the optic. The sharp is usuallyan outside corner rather than an inside corner. From a fluid standpointit is an angle greater than 180 degrees.

Referring now to FIG. 1A, a cut away view of a prior art lens 100 isillustrated with an oil 101 and a saline solution 102 contained withincylinder 110. The cylinder 110 includes two plates of optical material106. Each plate 106 includes a flat interior surface 113-114. Thecylinder 110 includes an interior surface that is essentiallyrotationally symmetric. In some prior art embodiments, one or moresurfaces may include a hydrophobic coating. Electrodes 105 are alsoincluded on or about the perimeter of the cylinder. An electricalinsulator may also be used proximate to the electrodes 105.

According to the prior art, each of the interior surfaces 113-114 isessentially flat or planar. An interface surface 112A is defined betweenthe saline solution 102A and the oil 101. As illustrated in FIG. 1A, theshape of the interface 112A is combined with the refractive indexproperties of the saline solution 102A and the oil 101 to receiveincident light 108 through a first interior surface 113 and providedivergent light 109 through a second interior surface 113. The shape ofthe interface surface between the oil 101 and the saline solution 102may be altered with the application of an electrical current to theelectrodes 105.

Prior art lens 100A illustrates a perspective view of the prior art lensillustrated at 100.

Referring now to FIG. 1B, the prior art lens 100 is illustrated in anenergized state. The energized state is accomplished by applying voltage114 across the electrodes 115. The shape of the interface surface 112Bbetween the oil 101 and the saline solution 102 is altered with theapplication of an electrical current to the electrodes 115. Asillustrated in FIG. 1B, incident light 108B passing through the oil 101and the saline solution 102B is focused into a convergent light pattern111.

Referring now to FIG. 2, a cut away view of a liquid meniscus lens 200with a front curve lens 201 and a back curve lens 202 is illustrated.The front curve lens 201 and the back curve lens 202 are positionedproximate to each other and form a cavity 210 therebetween. The frontcurve lens includes a concave arcuate interior lens surface 203 and aconvex arcuate exterior lens surface 204. The concave arcuate lenssurface 203 may have one or more coatings (not illustrated in FIG. 2).Coatings may include, for example, one or more of electricallyconductive materials or electrically insulating materials, hydrophobicmaterials or hydrophilic materials. One or both of the concave arcuatelens surface 203 and the coatings are in liquid and opticalcommunication with an oil 208 contained within the cavity 210.

The back curve lens 202 includes a convex arcuate interior lens surface205 and a concave arcuate exterior lens surface 206. The convex arcuatelens surface 205 may have one or more coatings (not illustrated in FIG.2). Coatings may include, for example, one or more of electricallyconductive materials or electrically insulating materials, hydrophobicmaterials or hydrophilic materials. At least one of the convex arcuatelens surface 205 and the coatings are in liquid and opticalcommunication with a saline solution 207 contained within the cavity210. The saline solution 207 includes one or more salts or othercomponents which are electrically conductive and as such may be eitherattracted to or repulsed by an electric charge.

According to the present invention, an electrically conductive coating209 is located along at least a portion of a periphery of one or both ofthe front curve lens 201 and the back curve lens 202. The electricallyconductive coating 209 may include gold or silver and is preferablybiocompatible. Application of an electrical charge to the electricallyconductive coating 209 creates either an attraction or a repulsion ofthe electrically conductive salts or other components in the salinesolution.

The front curve lens 201 has an optical power in relation to lightpassing through the concave arcuate interior lens surface 203 and aconvex arcuate exterior lens surface 204. The optical power may be 0 ormay be a plus or minus power. In some preferred embodiments, the opticalpower is a power typically found in corrective contact lenses, such as,by way of non-limiting example, a power between −8.0 and +8.0 diopters.

The back curve lens 202 has an optical power in relation to lightpassing through the convex arcuate interior lens surface 205 and aconcave arcuate exterior lens surface 206. The optical power may be 0 ormay be a plus or minus power. In some embodiments, the optical power isa power typically found in corrective contact lenses, such as, by way ofnon-limiting example, a power between −8.0 and +8.0 diopters.

Various embodiments may also include a change in optical powerassociated with a change in shape of a liquid meniscus 211 formedbetween the saline solution 207 and the oil. In some embodiments, achange in optical power may be relatively small, such as, for example, achange of between 0 to 2.0 diopters of change. In other embodiments, achange in optical power associated with a change in shape of a liquidmeniscus may be up to about 30 or more diopters of change. Generally, ahigher change in optical power associated with a change in shape of aliquid meniscus 211 is associated with a relatively thicker lensthickness 210.

According to some embodiments of the present invention, such as thoseembodiments that may be included in an ophthalmic lens, such as acontact lens, a cross cut lens thickness 210 of an arcuate liquidmeniscus lens 200 will be up to about 1,000 microns thick. An exemplarylens thickness 210 of a relatively thinner lens 200 may be up to about200 microns thick. Preferred embodiments may include a liquid meniscuslens 200 with a lens thickness 210 of about 600 microns thick. Generallya cross cut thickness of front curve lens 201 may be between about 35microns to about 200 microns and a cross cut thickness of a back curvelens 202 may also be between about 35 microns and 200 microns.

According to the present invention, an aggregate optical power is anaggregate of optical powers of the front curve lens 201 the back curvelens 202 and a liquid meniscus 211 formed between the oil 208 and thesaline solution 207. In some embodiments, an optical power of the lens200 will also include a difference in refractive index as between one ormore of the front curve lens 201, the back curve lens 202, oil 208 andthe saline solution 207.

In those embodiments that include an arcuate liquid meniscus lens 200incorporated into a contact lens, it is additionally desirous for thesaline 207 and oil 208 to remain stable in their relative positionswithin the curved liquid meniscus lens 200 as a contact wearer moves.Generally, it is preferred to prevent the oil 208 from floating andmoving relative to the saline 207 when the wearer moves, accordingly, anoil 208 and saline solution 207 combination is preferably selected witha same or similar density. Additionally, an oil 208 and a salinesolution 207 preferably have relatively low immiscibility so that thesaline 207 and oil 208 will not mix.

In some preferred embodiments, a volume of saline solution containedwithin the cavity is greater than the volume of oil contained within thecavity. Additionally, some preferred embodiments include the salinesolution 207 in contact with essentially an entirety of an interiorsurface 205 of the back curve lens 200. Some embodiments may include avolume of oil 208 that is about 66% or more by volume as compared to anamount of saline solution 207. Some additional embodiments may includean arcuate liquid meniscus lens wherein a volume of oil 208 that isabout 90% or less by volume as compared to an amount of saline solution207.

Referring now to FIG. 3, a cutaway of an edge portion arcuate liquidmeniscus lens 300 is illustrated. As discussed above, an arcuate liquidmeniscus lens 300 includes combined front curve lens 301 and back curvelens 302 components. The front curve lens 301 and back curve lens 302may be formed with one or more materials that are at least partiallytransparent. In some embodiments, one or both of the front curve lens301 and the back curve lens 302 include generally optically clearplastic, such as for example, one or more of: PMMA, Zeonor™ and TPX.

One or both of the front curve lens 301 and the back curve lens 302 maybe fashioned, for example via processes such as one or more of: singlepoint diamond lathing; injection molding; and digital mirror device freeforming.

One or both of the front curve lens 301 and the back curve lens 302 mayinclude a conductive coating 303, as illustrated, the conductive coating303 extending along a perimeter portion from 309 to 310. In somepreferred embodiments, a conductive coating 303 includes gold. The goldmay be applied via a sputter process, vapor deposition or other knownprocess. Alternative conductive coating 303 may include, by way ofnon-limiting example, aluminum, nickel, and indium tin oxide. Generally,the conductive coating 303 will be applied to perimeter areas of one orboth of the front curve lens 301 and the back curve lens 302.

In some embodiments, of the present invention, a back curve lens 302 hasa conductive coating 304 applied to specific areas. For example,portions about the perimeter of the back curve lens 302 may be coatedfrom a first boundary 304-1 to a second boundary 304-2. The goldcoatings may be applied for example via a sputter process or a vapordeposition. In some embodiments, a mask may be used to apply the gold orother conductive material in a predetermined pattern around one or moreperimeter portions of a front curve lens 301 or a back curve lens 302.Alternative conductive materials may be applied using various methodsand covering varying areas of the back curve lens 302.

In some embodiments, a conductive pass through, such as, for example oneor more holes or slots in a back curve lens 302 may be filled with aconductive filler material, such as, for example, a conductive epoxy.The conductive filler may provide electrical communication to aconductive coating on an interior surface of one or both of the frontcurve lens 301 and the back curve lens 302.

In another aspect of the present invention, one or both of the frontcurve lens 301 and the back curve lens 302 may be created from multipledifferent materials wherein an optical zone generally in a central areaof the front curve lens 301 and the back curve lens 302 (notillustrated) may include an optically transparent material and aperipheral zone may include an optically opaque area that includes anelectrically conductive material. The optically opaque area may alsoinclude one or more of control circuitry and energy sources.

In still another aspect, in some embodiments, an insulator coating 305is applied to a front curve lens 301. By way of non-limiting example,the insulator coating 305 may be applied in an area from a first region305-1 and extend to a second region 305-2. Insulators may include, forexample, Parylene C™, Teflon AF™ or other materials with variouselectrical and mechanical characteristics and electrical resistance.

In some specific embodiments, an insulator coating 305 creates aboundary area to maintain separation between the conductive coating 303and a saline solution 306 contained in a cavity between the front curvelens 301 and the back curve lens 302. Some embodiments accordinglyinclude an insulator coating 305 patterned and positioned in an one ormore areas of one or both of the front curve lens 301 and the back curvelens 302 to prevent a positively charged conductor 303 and negativelycharged saline solution 306 from coming into contact, wherein contact ofa conductor 303 and a saline solution 306 will result in an electricalshort. Embodiments may include a positively charged saline solution 306and a negatively charged conductor 303.

Still other embodiments may allow for a short between a conductor 303and a saline solution 306 as a reset function of circuitry associatedwith the operation of the lens 300. For example, a short condition mayinterrupt power source to the lens and cause the saline solution 306 andthe oil 307 to revert to a default position.

Some preferred embodiments include a conductor 303 that extends from anarea 309 on the interior of the cavity 311 to an area 310 external tothe cavity 311. Other embodiments may include a channel 312 through thefront curve lens or the back curve lens which may be filled with aconductive material 313, such as, for example, a waterproof conductiveepoxy. The conductive material 313 may form or be connected to anelectrical terminal external to the cavity. An electrical charge may beapplied to the terminal and conducted to the coating via the conductivematerial 313 in the channel 312.

The thickness of the insulator coating 305 may be varied as a parameterof lens performance. According to the present invention, chargedcomponents, including the saline solution 306 and the conductor 303, aregenerally maintained on either side of the insulator coating 305. Thepresent invention provides for an indirect relationship between thethickness of the insulator coating 305 and an electrical field betweenthe saline solution 306 and the conductor 303, wherein the farther apartthe saline solution 306 and the conductor 303 are maintained, the weakerthe electrical field will be.

Generally, the present invention provides that electrical field strengthmay fall off dramatically as insulator coating 305 thickness increases.The closer together the fields are, the more energy that will generallybe available to move a spherical liquid meniscus boundary 308. As adistance between the saline solution 306 and conductor 303 increases,the farther apart electrical fields of the saline solution 306 and theconductor coating 303 will be and therefore the harder it is to get thespherical meniscus boundary 308 to move. Inversely, the thinner theinsulator coating 305, the more sensitive movement of the sphericalliquid meniscus 308 is to defects in an insulator coating 305.Generally, even a relatively small hole in the insulator coating 305will short a lens 300 out.

In some embodiments, it is desirable to include a saline solution 306with density that is generally the same density of an oil 307 alsocontained within the lens 300. For example, a saline solution 306 maypreferably include a density that is within 10% of a density of an oil307 and more preferably the saline solution 306 will include a densitywithin 5% of a density of an oil and most preferably within about 1%. Insome embodiments, a concentration of salts or other components withinthe saline solution 306 may be adjusted to adjust the density of thesaline solution 306.

According to the present invention, an arcuate liquid meniscus lens 300will provide a more stable optical quality by limiting movement of theoil 307 in relation to the front curve lens 301 and the back curve lens302. One method of maintaining stability of movement of the oil 307 inrelation to one or both of the arcuate front curve lens 301 and the backcurve lens 302 is to maintain a relatively congruent density in the oil307 and the saline solution 306. In addition, due to the curve design ofthe interior surfaces of both the front curve lens 301 and the backcurve lens 302, the relative depth or thickness of a layer of salinesolution 306 is diminished as compared to a traditional cylindrical lensdesign. Accordingly, stability of a position of oil within the lens 300becomes more in order to avoid movement of the oil and possible breakingof the meniscus between the oil 306 and the saline solution 307.

In some preferred embodiments, the saline solution 306 provides a lowrefractive index as compared to the oil 307 which provides a relativelyhigh refractive index. However, in some embodiments it is possible toinclude a saline solution 306 with a higher refractive index as comparedto the oil 307 which in such cases provides a relatively lowerrefractive index.

An adhesive 308 may be used to secure the front curve lens 301 and backcurve lens 302 in place proximate to each other thereby retaining theoil 307 and saline solution 306 therebetween. The adhesive 308 acts as aseal so that there is no leakage of saline 306 or oil 307 from thecurved liquid meniscus lens 300.

Referring now to FIG. 4, a curved liquid meniscus lens 400 isillustrated with a liquid meniscus boundary 401 between the salinesolution 406 and oil 407. According to some preferred embodiments, ameniscus wall 405 is defined in the front curve lens 404 by a firstangular break in an arcuate wall extending between 402 and 403. Theliquid meniscus boundary 401 will move up and down the meniscus wall 405as charge is applied and removed along one or more conductive coatingsor conductive materials 408.

In some preferred embodiments, a conductive coating 403 will extend froman area internal to the cavity 409 holding the saline solution 406 andthe oil 407 to an area external to the cavity 409 containing the salinesolution 406 and oil 407. In such embodiments, the conductive coating403 may be a conduit of an electrical charge applied to the conductivecoating 403 at a point external to the cavity 409 to an area of theconductive coating within the cavity and in contact with the salinesolution 406.

Referring now to FIG. 5, a cut away view of an edge portion of anarcuate liquid meniscus lens 500 is shown with a front curve lens 501and a back curve lens 502. The arcuate liquid meniscus lens 500 may beused to contain saline solution 503 and oil 504. The geometry of thearcuate liquid meniscus lens 500 and the characteristics of the salinesolution 503 and oil 504 facilitate formation of a liquid meniscusboundary 505 between the saline solution 503 and oil 504.

Generally, a liquid meniscus lens may include: conductive coatings,insulator coatings, pathways, and materials present on or through thefront curve lens 501 and back curve lens 502. According to the presentinvention, a shape of a liquid meniscus boundary 505 and therefore acontact angle between the liquid meniscus boundary 505 and the frontcurve lens 501 change in response to an electrical charge applied to asurface of at least a portion of one or both of the front curve lens 501and the back curve lens 502.

According to the present invention, a change in an electrical currentapplied to the saline solution via the conductive coatings or materialschanges a position of the liquid meniscus boundary 505 along a meniscuswall 506. The movement takes place between a first sharp 506-1 and asecond sharp 506-2.

In preferred embodiments, the liquid meniscus boundary 505 will be at ornear the first sharp 506-1 when a first magnitude of electrical currentis applied to the lens, such as, for example, a voltage and currentcorrelating with an unpowered or rest state.

Application of a second magnitude of electrical current, sometimesreferred to as a powered state, may correlate with a movement of theliquid meniscus boundary 505 along the meniscus wall 506 generally inthe direction of the second sharp 506-2, causing the shape of the liquidmeniscus boundary to change.

In some embodiments, the meniscus wall 506 will be a smooth surface. Asmooth meniscus wall 506 surface may minimize defects in the insulatorcoating. Additionally, because random irregularities in surface texturemay result in uneven fluid motion and therefore cause uneven orunpredictable meniscus motion when energizing or de-energizing the lens,a smooth meniscus wall 506 is preferred. In some preferred embodiments,a smooth meniscus wall includes a peak to valley measurement along themeniscus wall 506 in the range of between about 1.25 nanometers to 5.00nanometers.

In another aspect, in some embodiments, it is desirable for the meniscuswall 506 to be hydrophobic, in which case a defined texture, such as anano-textured surface, may be incorporated in the design of the arcuateliquid meniscus lens.

In still another aspect, in some embodiments, the meniscus wall 506 maybe angled relative to an optical axis of the lens. The angle can rangefrom 0°, or parallel to the optical axis, to at or near 90°, orperpendicular to the optical axis. As illustrated, and in some preferredembodiments, the meniscus wall 506 angle is generally between about 30°and 50° in order for the arcuate liquid meniscus lens to function giventhe current contact angle between the liquid meniscus boundary 505 andthe insulator-coated meniscus wall 506. With the use of differentmaterials or with different optical objectives, such as telescopicvision, the angle of the meniscus wall 506 may be closer to 0° or 90°.

According to the present invention, an angle of a meniscus wall 506 maybe designed to accommodate a magnitude of movement along a meniscus wall506 upon application of a specified electrical voltage and current. Insome embodiments, as meniscus wall 506 angle increases, the ability tochange lens power generally decreases within given lens size and voltageparameters. Additionally, if the meniscus wall 506 is at or near 0°relative to the optical axis, the liquid meniscus boundary 505 will besteered nearly straight onto the front optic. Meniscus wall angle is oneof several parameters that can be tailored to provide various outcomesin lens performance.

In some preferred embodiments, the meniscus wall 506 is approximately0.265 mm in length. However, the angle of the meniscus wall 506 togetherwith the size of the overall lens will naturally affect meniscus wall506 length in various designs.

It may generally be considered that an arcuate liquid meniscus lens 500will fail if the oil 504 contacts the back curve lens 502. Therefore, inpreferred embodiments, the meniscus wall 506 is designed to allow aminimum clearance of 50 microns between the first sharp 506-1 and theback curve lens 502 at its nearest point. In other embodiments, theminimum clearance may be less than 50 microns, although the risk of lensfailure increases as the clearance is reduced. In yet other embodiments,the clearance may be increased to mitigate the risk of lens failure, butthe overall lens thickness will also increase which may be undesirable.

In still another aspect of some preferred embodiments of the presentinvention, the behavior of a liquid meniscus boundary 505 as it travelsalong a meniscus wall 506 may be extrapolated using Young's Equation.Although Young's Equation defines the balance of forces caused by a wetdrop on a dry surface and assumes a perfectly flat surface, thefundamental properties can be applied to the electrowetted lensenvironment created within the arcuate liquid meniscus lens 500.

When a first magnitude of electrical energy is applied to the lens, suchas, for example, when the lens is in an unpowered state, there will beachieved a balance of interfacial energies between the oil 504 andsaline solution 503, herein referred to as the liquid meniscus boundary505, the oil 504 and meniscus wall 506, and the saline solution 503 andmeniscus wall 506, resulting in an equilibrium contact angle between theliquid meniscus boundary 505 and the meniscus wall 506. When a change inmagnitude of voltage is applied to the arcuate liquid meniscus lens 500,the balance of interfacial energies will change, resulting in acorresponding change in contact angle between the liquid meniscusboundary 505 and the meniscus wall 506.

The contact angle of the liquid meniscus boundary 505 with theinsulator-coated meniscus wall 506 is an important element in the designand function of the arcuate liquid meniscus lens 500 not only due to itsrole in the Young's Equation in movement of the liquid meniscus boundary505, but also because the contact angle is used in conjunction withother features of the arcuate liquid meniscus lens 500 to limit meniscusmovement.

Discontinuities, such as sharps 506-1 506-2, at both ends of themeniscus wall 506 act as boundaries for liquid meniscus 505 movementbecause it would require a significant change in voltage to effect alarge enough change in liquid meniscus contact angle to move the liquidmeniscus boundary 505 past one of the sharps. By way of non-limitingexample, in some embodiments, a contact angle of the liquid meniscusboundary 505 with the meniscus wall 506 is in the range of 15 to 40°whereas the contact angle of the liquid meniscus boundary 505 with thestep 507 below the second sharp 506-2 is perhaps in the range of 90 to130° and in some preferred embodiments about 110°.

A voltage applied to the lens may result in movement of the liquidmeniscus boundary 505 along the meniscus wall 506 toward the secondsharp 506-2. The natural contact angle of the liquid meniscus boundary505 with the insulator-coated meniscus wall 506 will cause the liquidmeniscus boundary 505 to stop at the second sharp 506-2 unlesssignificantly more voltage is supplied.

At one end of the meniscus wall 506, a first sharp 506-1 generallydefines one limit beyond which the liquid meniscus boundary 505 will nottypically move. In some embodiments, the first sharp 506-1 isconstructed as a sharp edge. In other preferred embodiments, the firstsharp 506-1 has a defined small radial surface which can be created withless possibility of defect. Conductive, insulator, and other possibledesired coatings may not deposit evenly and predictably on a sharp edge,whereas a defined radius edge of the radial surface can be coated morereliably.

In some embodiments, the first sharp 506-1 is constructed at about a 90°angle with a defined radius of about 10 microns. The sharp may also becreated with less than a 90° angle. In some embodiments, a sharp with alarger angle than 90° may be used to increase the sturdiness of thesharp, but the design would then take up more lens space.

In various embodiments, a defined radius of a sharp 506-1 506-2 may bein the range of 5 microns to 25 microns. A larger defined radius may beused to improve the reliability of the coatings, but at the cost ofusing more space within the tight tolerances of the lens design. Inthis, as in many other areas of lens design, tradeoffs exist betweenease of construction, optimization of lens functions, and minimizingsize. A functional, reliable arcuate liquid meniscus lens 500 may bemade using a wide range of variables.

A second sharp 506-2, includes a feature designed to limit oil movementwhen voltage is applied to the arcuate liquid meniscus lens 500. Thesecond sharp 506-2 may also include, in some embodiments a sharp, or inother embodiments, the second sharp 506-2 may include a defined radiusof between 5 and 25 microns, most preferred 10 microns. A 10 micronradius performs well as a sharp and can be created using single pointdiamond turning lathe or injection molding processes.

A vertical, or nearly vertical step 507, extending to a start of theoptical area 508 of the front curve lens 501 may be included on a sideof the second sharp 506-2 opposing the meniscus wall 506. In someembodiments, the step 507 is 120 microns in height, although it could bein the range of 50 to 200 microns.

In some embodiments, the step 507 may be angled at about 5° from opticalaxis. In other embodiments, the step 507 angle may be as little as 1° or2° or may be angled more than 5°. A step 507 that is less angled fromoptical axis will generally act as a more effective limiter of meniscusmovement because it would require a greater change in the contact angleof the liquid meniscus boundary 505 to move off of the meniscus wall 506and onto the step 507. The transition from the step 507 to the start ofthe optical area 508 is a 25 micron radius. A larger radius wouldunnecessarily consume more space within the lens design. A smallerradius is possible and may be implemented if necessary to gain space.The decision to use a defined radius rather than a theoretical sharp inthis area as well as others in the lens is based, in part, on thepotential move to an injection molding process for lens elements. Acurve between the step 507 and the start of the optical area 508 willimprove plastic flow during the injection molding process and result ina lens with optimal strength and stress-handling characteristics.

Referring now to FIG. 6A, in one of many possible embodiments, a concavemeniscus wall 601 is depicted. The concave meniscus wall 601 componentof the arcuate liquid meniscus lens, if viewed separately from the restof the arcuate liquid meniscus lens, is a segment of a torus, shown as aperspective view in FIG. 7. As depicted in FIG. 7, in this embodimentthe meniscus wall 701 is concave from the optical axis and of aconsistent length between the first sharp 702-1 and the second sharp702-2 around the entire lens.

FIG. 6A depicts a possible embodiment in which a meniscus wall 601,concave from the optical axis, is placed approximately at a 45° anglefrom optical axis in an arcuate liquid meniscus lens containing oil 602and saline solution 603. The liquid meniscus boundary 604A contacts themeniscus wall 601 at 605A, generally near the end of the meniscus wall601 closest to the first sharp 608. The contact angle is indicated by606A. After voltage is applied, as seen in FIG. 6B, the liquid meniscusboundary moves along the meniscus wall 601 to 605B, generally toward thefront curve lens 607, resulting in contact angle 606B.

In general, a liquid meniscus lens with a concave meniscus wall placedat a given angle relative to the optical axis, as shown in FIG. 6C, willexhibit less change in lens power for a given amount of applied voltagethan a liquid meniscus lens with a linear meniscus wall placed at asimilar angle relative to the optical axis. A liquid meniscus lens witha linear meniscus wall is more fully described in U.S. PatentApplication Ser. No. 61/359,548, entitled “LENS WITH CONICAL FRUSTUMMENISCUS WALL” and filed on Jun. 29, 2010.

A specific change in applied voltage causes a change in the balance ofinterfacial energies and therefore causes a corresponding change incontact angle between the liquid meniscus boundary and the meniscuswall. On a linear meniscus wall, the change in contact angle results ina relatively more significant movement of the liquid meniscus boundaryalong the meniscus wall, whereas the movement is relatively lesssignificant on a concave meniscus wall, FIG. 6C.

While the invention has been described with reference to particularembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from thescope of the invention.

Therefore, it is intended that the invention not be limited to theparticular embodiments disclosed as the best mode contemplated forcarrying out this invention, but that the invention will include allembodiments falling within the scope and spirit of the appended claims.

The invention claimed is:
 1. An optical lens comprising: a front curvelens comprising a front curve lens exterior surface and a front curvelens interior surface, wherein both said front curve lens exteriorsurface and said front curve lens interior surface comprise an arcuateshape; a back curve lens comprising a back curve lens interior surfaceand a back curve lens exterior surface, wherein both said back curvelens interior surface and the back curve lens exterior surface comprisean arcuate shape, said back curve lens positioned proximate to saidfront curve lens such that said front curve lens interior surface andsaid back curve lens interior surface form a cavity therebetween and anoptical axis through said front curve lens and said back curve lens; avolume of saline solution and oil contained within the cavity formedbetween said front curve lens interior surface and said back curve lensinterior surface, said volume of saline solution and oil comprising ameniscus therebetween; and a meniscus wall comprising a general shape ofa conical frustum with at least a portion of the conical frustum concavetoward the optical axis.
 2. The optical lens of claim 1 additionallycomprising a conductive coating on at least a portion of said meniscuswall.
 3. The optical lens of claim 2 wherein the volume of oil is lessthan the volume of saline solution contained within the cavity.
 4. Theoptical lens of claim 3 wherein the front curve lens exterior surfacecomprises an optical power other than about
 0. 5. The optical lens ofclaim 3 wherein the front curve lens interior surface comprises anoptical power other than about
 0. 6. The optical lens of claim 3 whereinthe back curve lens exterior surface comprises an optical power otherthan about
 0. 7. The optical lens of claim 3 wherein the back curve lensinterior surface comprises an optical power other than about
 0. 8. Theoptical lens of claim 3 additionally comprising a channel through one orboth of the front curve lens and the back curve lens and a conductivematerial filling the channel.
 9. The optical lens of claim 8additionally comprising a terminal in electrical communication with theconductive material filling the channel.
 10. The optical lens of claim 9wherein application of an electrical charge to the terminal causes achange in the shape of the meniscus.
 11. The optical lens of claim 3additionally comprising an insulator coating along at least a portion ofthe interior surface of the front curve lens, wherein the insulatorcoating comprises an electrical insulator.
 12. The optical lens of claim11, wherein the insulator comprises one of Parylene C™ and Teflon AF™.13. The optical lens of claim 11 wherein the insulator comprises aboundary area to maintain separation between the conductive coating anda saline solution contained in the cavity between the front curve lensand the back curve lens.
 14. The optical lens of claim 3 wherein anangle of the conical frustum with at least a portion of the conicalfrustum concave toward the optical axis comprises between about 30.degree. and 50 .degree.
 15. The optical lens of claim 14 additionallycomprising a meniscus sharp adjacent to the meniscus wall, said sharpcomprising a angular feature for containing the volume of salinesolution and oil.
 16. The optical lens of claim 15 wherein the radialsurface portion comprises a radius in the range of 5 microns to 25microns.
 17. The optical lens of claim 14 wherein the sharp comprises aradial surface portion.
 18. The optical lens of claim 2 wherein thevolume of oil comprises about 66% or more by volume as compared to anamount of saline solution.
 19. The optical lens of claim 2 wherein thevolume of oil comprises about 90% or less by volume as compared to anamount of saline solution.
 20. The optical lens of claim 2 wherein thevolume of oil comprises a density about equal to a density of the salinesolution.
 21. The optical lens of claim 2 wherein the volume of oilcomprises density within about 10% of a density of the saline solution.22. The optical lens of claim 2 wherein the volume of oil comprisesdensity within about 5% of a density of the saline solution.
 23. Theoptical lens of claim 2 wherein the conductive coating extends from anarea interior to the cavity to an area external to the cavity.
 24. Theoptical lens of claim 23, wherein the area of conductive coatingexternal to the cavity forms an electrical terminal for providing anelectrical charge to the liquid meniscus lens.
 25. The optical lens ofclaim 23 wherein the saline solution and the oil form a meniscus and anapplication of an electrical charge to the area of conductive coatingexternal to the cavity causes a change in position of contact of themeniscus along the meniscus wall.
 26. The optical lens of claim 23wherein the electrical charge comprises a direct current.
 27. Theoptical lens of claim 23 wherein the electrical charge comprises about20.0 volts.
 28. The optical lens of claim 23 wherein the electricalcharge comprises between about 18.0 volts to 22.0 volts.
 29. The opticallens of claim 23 wherein the electrical charge comprises about 5.0volts.
 30. The optical lens of claim 23 wherein the electrical chargecomprises between about 3.5 volts to about 7.5 volts.
 31. The opticallens of claim 1 wherein the meniscus wall is formed in one or both ofthe front curve lens and back curve lens and bordering the meniscusformed between the saline solution and oil.